Improvement in processes for treating copper ores



UNITED STATES PATENT :iQFEIG-E FRANCIS zwrcxn, OF "JERSEY! own-NEWJEEsEY.

IMPROVEMENT IN PROCESSESFOR'TREATINGCOPPER. OR ES- Specification formingpart of Letters Patent No. 153,796,- dated August 4, 1874; applicationfiled May 16, 1874.

, or in auxiliary manner to other processes for the extraction of gold,silver, andcopper therefrom. The invention consists of a combination ofoperations, viz., smelting ofthe :ores in a reverberatory furnace to amat with admixture of sulphate of soda, forthe purpose of disintegrationoxidation of the disintegrated mat in a furnace similar to a commonroast-furnace suitably adapted to prevent the heat from rising above thedesired degree; repetition of this oxidation after the first isfinished, and the product of it has been soaked with water dissolvingthe sulphate of copper formed duringsaid oxidation in atank with water,and after removal of the solutiondis- 1 solving the copper still left inresidue with a solution of sulphate of iron, this latter process to berepeated as long as any copper .is left in the residue, the copper insolution tobe precipitated with iron. The residue, containing peroxideof iron and all the gold and silver, being much reducedin-bulk can betreated I by any known method for the extraction of the gold and silver,or used as flux for smelting the ores, and to accumulate the bullion asfar as desired. I I As the I success of this process. depends mainlyupon the perfect disintegration and treatment of the ores during theoxidation or calcination processes, I will more fully describe the same,and the tests for controlling the progress of the operations.

First, the sulphureted copper ores are smelted either alone or blendedwith other ores in a reverberatory furnace to a-mat or regulus, and arethen treated, after the removal of the dross,

. with sulphate of soda or salt-cake, say, about ten per cent. of theweight of the mass to produce the disintegration of the mass to. finepowderwithout vmechanical. grinding, in the well-known method.

Second, the powdered mat is to be calcined or better oxidized .in afurnace similar to a common roastfurnace, with this difference, however,that the floor. is not made of solid masonry, but cast-iron plates orbrick tiles .restin g on flat-laid bricks, for allowing the freecirculation 'of the air underjthe floor for keepin g it cool, andpreventing thereby" the decomposition of the sulphate ofcopper aftersame is formed. -The furnace is furthermore divided by alow brick wallinto two compartments,

the front part near the fire-bridge, and the .rear'partof-largersizetoward the chimney. From the rear compartment preferably several fines.ought to connect with the smoke-stack,

in order to better spread the flame over the same. The matis firstcharged into the rear compartment,.say, in quantities of about threethousand pounds, and spread out there to lay not over four or fiveinches deep,.to be exposed to, amoderate flamingfire, by which it willbe soon, ignited, and burnwith a faint blue flame all over the'same.Aslong as this continues the firemust be kept low, and thewhole mass beoften stirred. After the blue flame has entirely disappeared the firemustbe slightly in- ..creased, .so as to maintain afaiut cherry-redheatforabout twohours longer. After that timethe charge is drawn out,and deposited in proximity to the doors of the front compartnlent, whereit will cool down sufficiently to -be mixed with water. until it, hasthe consist-- .ency, of stiifmasons mortar, in whichstate it is to beleft. The rear compartment is, during 'the (preparationv of .this mass,charged again with disintegrated mass for oxidation. The moistened. massbecomes after'four or fivehoursoutWardIydry and hard, and has to bestirred. up with acopper spade and g the lumps mashed,'to be thencharged before being completely dry. into the front compart- .ment.

Third, the mass is there exposedjfor two or. three: hours to. a darkcherry-red heat, slightly more .than the former, and racked thoroughlyand often, to. be then .drawn out iclean. Shouldat any time the heatincrease The following tests serve as a guide in treat-.

ing the mass in the oxidizing-chamber: If the part taken out shows aftercoolingolive-green spots, it is not sufiiciently long in the furnace, ornot heated enough. If it shows a pale-brick color, with a gray dustytinge, it is' in the re-' quired condition. If it should show adarkbrown color, plied was too great, and the mass is partly roasteddead, so that less copper will be precipitated, and the treatment withconcentrated iron solution has to be prolonged. The oxidized matter isfurther treated wet, in a series of tanks, of which No. 1 may be made ofiron with a fire under it, or of wood if heated by steam. Tank No. 2 isplaced in front of the former and below, made of wood, with several plugholes on one side. Tank No. 3 is in front of and under No. 2, andserves, as precipitatingtank, is made of wood if steam be at hand forheating, of copper if it is to be heated by a fire below. Tank No. 4 ismade of wood large and shallow, and contains the more or lessconcentrated solution of sulphate of soda and iron coming frompreciptating tank. Tank No. 5 is made like No. 4, and contains verydiluted solutions of copper, iron, and soda sulphates, obtained fromwashing residues,

and intended to be evaporated and to be used in the other operationsinstead of pure water. Tank No. 6 is also made like the former, andcontains diluted solutions of sulphates of iron and copper dBP'OSited'for slow evaporation, and to be, used for washing residues containing nosplphate of soda.

It is obvious that instead of tanks Nos. 4, 5, and 6 any number ofsmaller tanks instead of larger ones may beused'.

Fourth. The mass drawn from inner compartment is thrown hot into tankNo. 2, which was filled previously with water or liquid from tank No. 5,sufficiently to cover the mass when spread and settled to about three orfour times its height. After stirring well and trimming the mass more tothe side opposite the plugholes, and being settled well the solution isallowed to run down into tank No. 3 through a filter hung below the plugand acidulated with a few ounces of sulphuric acid.

Fifth. The copper is here precipitated with scrap iron or iron sponge orboth at full boiling heat. The residue in tank No. 2 is to be washedonce or twice with pure water or with liquid from tank No. 5. Thoseliquids are to be used in preference to water in order to avoidunnecessary increase of their bulk. After the wash water becomes weak incopper it will be thrown back into tank No. 3, whence it'came. Theprecipitation being completed the remaining liquid is to be drawn hotfrom precipitation-tank, and poured back on residue in tank No. 2,stirred well, and

bordering on black, the heat ap duce sub-salts,

after settling let down once more into No. 3 for precipitation, afterwhich it is poured into tank No. 4 for evaporation to recover the sodaand iron salts.

Sixth. The residue which has now lost from fifty per cent to eighty percent of the copper it contained and half of its weight is furthertreated with a fully concentrated boiling hot solution of sulphate ofiron run down on it from tank No. l in sufficient quantity to cover iit" three or four times, and alter stirring it ;well several timesduring one hour, allowing it to settle, the solution is drawn into thepre- This treatment with iron socipitation-tank.

accordlution is to be repeated once or twice,

ing to richness of mass in copper until the latter is all, or nearlyall, extracted. The water used to wash the residue at last after gettingweak in copper is returned to tank No. 6, whence it came, the liquid,after precipitation, to be returned to tank No. 1. If circumstancesadmit, instead of throwing the oxidixed mass hot into tank No. 2, as de'scribed in operation fourth, it is more preferable to soak it again withwater and leave it in a bin, the longer the better, stirring it up onceper day, and keeping it damp. This willproand the fall of copper infirst The residue,

precipitation will be greater.

which has shrunk in the treatment of rich mass to less than two-fifthsin weight, contains practically nothing but peroxide of iron, and allthe silver and gold which the ores contained, and either practically nocopper, or as much as was left in it purposely for shortening process.If rich in bullion it will at once be delivered over to extraction byany of the known methods; if poor, it goes back to smelting as a fluxfor the ores which are, with rare exceptions, silicious, and are in needof iron for flux. The bullion can be accumulated with the repetitions ofthis proceeding to any extent desired.

The residue from pure copper ores being peroxide of iron can be easilyconverted into iron sponge for precipitation, which at once will recoverwhat copper was left in it, or it may be used, as mentioned above, forflux, or both uses may be made of it simultaneously. For the treatmentof mass above thirty-five percent. this method is impracticable as aself-sustaining process, but it may be made a great auxiliary to otherprocesses.

Having thus described my invention, I claim as new and desire to secureby Letters Patent- 1. In combination with the process of disintegrationof the copper ore by smelting with sulphate of soda, the process ofoxidization of the disintegrated mass in a furnace having a floor madeof cast-iron plates or thick tiles resting on flat-laid bricks, for thepurpose of allowing the free circulation of the air under the floor forkeeping it cool, and preventing thereby the decomposition of thesulphate of 3.- The process of treating the oxidized matter in a seriesof tanks, arranged and constructed' as described, for the purposes of soi lution and precipitation, substantially as and for-thepurposespec-ified. V FRANCIS "ZWIGKL,

Witnessesz;

PAUL Gown, 1. B. MOSHER.

